1. Field of the Invention
The present invention relates to a electromagnetic or dynamoelectric coupling device, and more particularly to a system for dissipating heat from the inductor drum of such a device.
Electromagnetic couplings of the type are well known in the art and include a rotor which is disposed within a rotatable inductor drum. A coil is energized to generate a magnetic field which electromagnetically couples the rotor and drum so that torque may be transferred therebetween. The passage of this magnetic field through the rotor and inductor drum results in the generation of heat during the transmission of torque partially as a result of "slip" between the rotor and the inductor drum (power in=power out+slip (heat) or slip (heat)=shaft power in minus shaft power out). The dissipation of heat has long been a problem in electromagnetic couplings and many different types of cooling systems have been tried in an effort to effectively dissipate the generated heat. In general, heat build up limits the speed ratio of the coupling. Thus, by increasing the heat dissipation capability of a particular size coupling, the speed ratio for that coupling can be increased.
2. Prior Art
The Jaeschke U.S. Pat. Nos. 4,362,958 and 3,996,485 is both disclose an electromagnetic coupling and a rod cooling system therefor.
The Jaeschke U.S. Pat. Nos. 3,316,429 and 2,827,580 disclose an inductor drum and supporting construction for an electromagnetic machine. These patents discloses a steel inductor drum which includes a cast aluminum cooling fin structure integrally formed therewith by die casting onto the steel drum. While such assembly provides efficient heat dissipation from the inductor drum it is also very costly due to the fact that the aluminum must be die cast directly onto the steel drum so that the aluminum is metalugically bonded to the drum so that heat moves from the drum to the aluminum finned structure. The Wheeler U.S. Pat. No. 3,824,684 includes a method of assembling a plastic housing of an electric motor device to an aluminum heat sink by deforming plastic pins integrally formed on the housing into openings in the aluminum heat sink. The plastic does not provide a good heat conductor.